STATE GEOLOGIST. 49 
suddenly and the resulting liquid slag is not viscous. Alumina especially 
is a strong agent towards producing viscosity. 
Prof. N. W. Lord defines the limits of slag composition by a very 
convenient diagram: 
Calcareous 
6ROAI,O, 
2ROSi0, ROSi0, 
Singulo Silicates Area of Bi-silicates 
Basic slags au Fusible Acid Slags 
Stony, melt suddenly. Slags. Vitreous,soften gradually 
Very liquid 
Oxygen ratio 1 : 1 Oxygen ratio 1 :.2 
3ROAI,O, 
Aluminous. 
The oxygen ratio of Al,O,: SiO, should lie between 1:3 and 1:2. 
This is equivalent to saying thatthe limits should lie between one molecule 
of alumina to 4.5 molecules of silica and one molecule of alumina to 3 
molecules of silica. . Expressed in ordinary relations by weight the 
limits are: 1 part of alumina : 2.64 parts of silica and I part of alumina : 
1.76 parts of silica. 
No complete table or curves showing the melting points of slags have 
as yet been prepared. R. Akerman* has determined the heats of fusion 
of singulo-silicate slags for a series of alumina-lime ratios: 
Oxygen 
Ratio ; 
0.20 | 0.25 | 0.30) 0.40| 0.50) 0.70 | 0.90} 1.00 | 1.20) 1.50) 2.00) 2.35 
Alumina 
Lime. 
Total heat 
of Fusion 
per unit AQ SE AO oSOM MOOS POLO MINS4We leOoOMlOOl oni 2400) 2430 4en 
Weight. 
Calories. 
Gredt** gives the formation temperatures of singulo-silicates, 
2ROSi0,, for a number of alumina-lime oxygen ratios: 
*Stahl und Hisen, 1890, p. 24. 
** Jueptner’s Siderology, p 296. 
4—S. G. Bull. 3. 
